Chemical Problems ideal synthesis

This closure property is also inherent to a set of differential equations for arbitrary sequences Uk in macromolecules of linear copolymers as well as for analogous fragments in branched polymers. Hence, in principle, the kinetic method enables the determination of statistical characteristics of the chemical structure of noncyclic polymers, provided the Flory principle holds for all the chemical reactions involved in their synthesis. It is essential here that the Flory principle is meant not in its original version but in the extended one [2]. Hence under mathematical modeling the employment of the kinetic models of macro-molecular reactions where the violation of ideality is connected only with the short-range effects will not create new fundamental problems as compared with ideal models. 

Notwithstanding all its advantages, the principle of solid-phase synthesis cannot be applied to all kinds of chemical reactions. Although reactants are used in excess, reaction is not always quantitative. The resulting impurities cannot be separated on the solid phase, giving rise to separation problems particularly in multi-step systems. Moreover, only limited use can often be made of conventional analytical methods (NMR, MS). Recent methods of 13C-NMR spectroscopy on solid phases [21] or in gel phases [22] are ideally suited for solid-phase synthesis, but are not universally available owing to the expensive instrumentation. 

When the statistical moments of the distribution of macromolecules in size and composition (SC distribution) are supposed to be found rather than the distribution itself, the problem is substantially simplified. The fact is that for the processes of synthesis of polymers describable by the ideal kinetic model, the set of the statistical moments is always closed. The same closure property is peculiar to a set of differential equations for the probability of arbitrary sequences t//j in linear copolymers and analogous fragments in branched polymers. Therefore, the kinetic method permits finding any statistical characteristics of loopless polymers, provided the Flory principle works for all chemical reactions of their synthesis. This assertion rests on the fact that linear and branched polymers being formed under the applicability of the ideal kinetic model are Markovian and Gordonian polymers, respectively. 

The first problem is the key issue. The immediate approach is to see the reactor synthesis as the inverse problem of the decomposition of a real reactor in compartments of ideal mixing patterns. Thus, the chemical reaction network would consists of a combination of ideal models, CSTR s and PFR with connections and by-pass streams. 

This chapter has illustrated the importance of the (3-mannosidic linkage within biological systems, and problems encountered with its synthesis. A number of chemical preparative methods have been compared, but it is obvious that there is no one, ideal method of universal utility. As with all carbohydrate chemistry, a careful assessment of the proposed preparative route must be performed before a specific technique for the incorporation of the 3-mannosidic linkage is selected and pursued. 

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